For over a century crutches and canes have remained virtually unchanged. Modifications to the crutch or cane itself have generally focused on ergonomic improvements in the physical structure versus functional improvements to mobility. As such, modern ambulatory aids continue to suffer from many of the same functional limitations that plagued their predecessors.
An example of an early crutch, in U.S. Pat. No. 127,028 issued May 21, 1872, involves the use of a round rubber tip made of respective layers of rubber and canvas, each exposed at the tip, to prevent the crutch from slipping on a wet surface. The use of a passive curved rocker provided at the lower end of the crutch to increase the progression or ground covered with use of the crutch is taught by U.S. Pat. No. 267,680 issued Nov. 21, 1882. A pneumatic cushion is used to form a curved rocker or bearer at the tip of the crutch in the patent to Mueller, U.S. Pat. No. 1,254,061 issued Jan. 22, 1918. The U.S. Pat. No. 1,277,009 to Weldon, issued Aug. 27, 1918, teaches the use of curved segmental base pieces at the tip of the crutches for ground engagement.
More recently, examples of annular crutch tips with features to resist slipping when engaged with the ground are shown by U.S. Pat. Nos. 3,040,757; 4,098,283; 4,411,284; 4,237,915 and 4,708,154. A radial crutch tip assembly with a base bottom surface and a resilient boot having a shape of a rocker is disclosed by Davis in each of U.S. Pat. Nos. 5,353,825; 5,409,029 and 5,465,745.
In other examples of walking aids, Wilkinson, U.S. Pat. No. 4,899,771, provides a foot member for the walking aid which is curved upwardly at its front and back ends to permit limited rolling of the foot member when used with a cane or crutch during a walking procedure. Similarly, Stephens discloses in U.S. Pat. No. 5,331,989 curving the front, rear and inner sides of the foot member of a walking aid to permit limited rolling of the crutch tip laterally as well as forward and backward.
Galan, in U.S. Pat. No. 5,829,463 provides the crutch tip with a heel portion or extension extending rearwardly from the tip at an upward angle. The heel portion is used to prevent slipping when the user is rising from a seated position. Semanchik et al. disclose in U.S. Pat. No. 4,493,334 a walking aid having a foot pad shaped with a curved sole to simulate an anatomical foot for achieving a rocking movement in use by imitating the phases of a normal gait, i.e. heel strike, foot flat and toe off. A published U.S. patent application, US 2001/0027802 A1 to McGrath, is directed to a walking aid comprising a shaft and a foot assembly, in which the foot assembly includes in combination a sleeve member and a foot member adapted for relative axial sliding movement and including resilient movement-restraint means for alleviating problems from shock loading transferred up the walking aid to the user's hand, wrist, arm and shoulder.
One of the single largest deficiencies of conventional walking assistance devices is the excessive amount of energy needed to stabilize the walking system (the device and the user's body) with the ground, and to efficiently move the user's body through space. In fact, a crutch user expends as much as 2.5 times more energy to move his/her body mass, in space, as compared to an able bodied person. Furthermore, the lack of sufficient surface area at the ground engaging surface of a walking assistance device engenders other dangers such slippage on uneven or slick surfaces. While improvements have been made with respect to the surface area at the point of contact for walking assistance devices, these improvements have been one-dimensional due to the limitations of the designs. It has been found by Applicants that the principal limitation to even the most progressive crutch or cane tip, with respect to surface area and/or surface textures, is the inability of these devices to stabilize the walking system while simultaneously translating the vertical forces associated with crutch/cane ambulation into forward propulsion and mobility. There is a need for an improved mobility assistance apparatus capable of stabilizing the walking system while lessening the user's necessary energy expenditure and discomfort associated therewith. More particularly, there is a need for a low cost, high function mobility assistance apparatus having improved loading response shock absorption and sagittal plane positive kinetic power which is needed for doing the work of walking. There is also a need for such an apparatus which is adaptable for use on different terrain/ground surfaces including ice, snow and mud.